Switch mechanism



July 31, 1928. 1,678,858

c. H. HODGKINS SWITCH MECHANI SM Filed April 11, 1922 2 Sheets-Sheet 1 INVENTOR Char/e5 Hoag/r/ns WITNQE E July 31, 1928. 1,678,858

(3. H. HODGKINS SWITCH MECHANI SM Filed April 11, 1922 2 Sheets-Sheet 2 INVENTOR ATTO'REY Patented July 31. 1928.

UNITED STATES PATENT E CHARLES H. nomxms, or PITTSBURGH, PENNSYLVANIA, ASSIGNQB, To wnsmccinousn ELECTRIC & MANUFACTURING comranv, a conrona'rron or rnnnstra- VANIA.

SWITCH MECHANISM.

Application filed April 11, 1922. Serial 170. 551,608.

This invention relates to switch mechanism and particularly to motor-starting switch mechanism for a three-pole circuit and having an overload and low-voltage control mechanism for opening the switch under predetermined circuit conditions.

It has been customary to mount overload and low-voltage controlling mechanism exteriorly of the switch housing in a separate compartment and to also mount the electromagnetic switch-operating mechanism in a similar exterior compartment. This construction necessitates comparatively complicated mechanical connections between the operating magnet and the switch, as well as a relatively expensive housing structure.

One object of my invention is to provide a switch mechanism, of the above character, wherein the electromagnetic switch-operating mechanism and the current-responsivemagnet controlling mechanism are mounted in compact relation within a single housing enclosing the switch mechanism.

Another object of my invention is to provide a switch mechanism, having the above characteristics, wherein the field member of.

the electromagnetic switch serves as a bearing and sole support for the switch shaft, and wherein the armature of the magnet is secured directly to the shaft for operating the switch shaft.

Another object of my invention is to provide a switch mechanism, of the above character, wherein the electromagnet and. movable switch members may be removed bodily from the casing, as a unit, for thepurpose of inspection and repair.

A further object of my invention is to provide a switch mechanism whereinthe stationary contact members of the switch are mounted'upon a single removable insulating support and wherein the current-responsivemagnet controlling devices are mounted directly upon the contact members, thus constituting a compact unitary structure that may be readily removed or replaced as a unit.

These and other objects, that will be made apparent throughout the further description of my invention, are attained by means of the switch mechanism hereinafter described and illustrated in the accompanying drawin wherein:

igure 1 is a transverse section through the switch mechanism taken on the line I-I of Fig. 2 and showing portions of the switch mechanism in side elevation.

Fig. 2 is a transverse section through the switch mechanism taken on the line IL-II of Fig. 1 and showing theswitch mechanism in front elevation, and

Fig. 3 is a wiring diagram showing the manner in which the switch mechanism is related to the electrical circuit.

Referring to the drawings, and articularly to Fig. 3 wherein the wiring iagram of the switch mechanism is illustrated, it will be seen that the switch mechanism is intended for use as a motor-starting switch having current-responsive relay mechanism for causing the switch to be opened under overload or low-voltage conditions in the circult.

A switch bar or shaft 4, carrying four switch arms 5, 6, 7 and 8, is actuated by means of an electromagnet armature 9 that is responsive to energization of an electromagnet coil 11. The three load conductors 12, 13 and 14 are connected, respectively, to the switch members 5, 6 and 8. Four stationary contact members 15, 16,17 and 18 are provided for engagement with the switch members 5, 6, 7 and 8, respectively. Feed conductors 19 and. 22 are connected to the contact members and 18, respectively, through bimetallic thermal-responsive conductor strips 23 and 24, respectively, and a neutral feed conductor 25 that is connected to the contact member 16.

The electromagnetic coil 11 is connected across the conductors 22 and 12 or across the line by means of a contact member 31 that is normally in engagement with the bimetallic strip 24, a conductor 27, conductor 28, normally open starting switches 32, conductor 29, normally closed stop switches 33, conductor 34, contact member 26, bimetallic strip 23 and switch contacts 15 and 5 to load conductor 12. When the switch contacts 17 and 7 are in en agement, the circuit through the starting switches 22 is shunted and current flows directly through the conductor 29 to the stopping switches 33.

The switch members are normally held in open position by means of a spring mechanism to be hereinafter described. The switch is adapted to be controlled by the auxiliary normally open push-button starting switches 32 and normally closed stopping switches 33 which may be arranged in any number and disposed at any desired remote points, in the manner indicated in the diagram.

The starting switches 32 are arranged in parallel relation between conductors 28 and 29 and serve to close the circuit through the coil 11 when the main switch 4 is open. The stopping switches 33 are connected in series with the conductor 34 and serve to interrupt the circuit through the coil 11 when any one of the stopping switches is open. Inasmuch as the stopping switches are normally closed, the closing of any one of the starting switches 32 will close the circuit through the coil 11 and cause the switch shaft 4 to be moved to closed position.

In order to start the motor, one of the starting switches 32 is closed momentarily, which causes the switch shaft 4 to be closed. Current then flows through the feed conductor 19 and through the bimetallic strip 23 to the load conductor 12. The bimetallic strip 23 comprises a bimetallic plate slotted, as indicated in the diagram, to provide an elongated path through the bimetallic plate so as to amplify the heating effect.

As the bimetallic plate becomes heated, it is bent away from the conductor 26, as indicated in dotted lines in Fig. 3. The plate is so designed that excessive heating, such as results from overload conditions in the circuit, causes the free end thereof to be moved out of engagement with the contact member 26. The instant the circuit is interrupted through the coil 11, a spring, previously referred to, causes the switch shaft 4 to be moved to open position.

The current from the feed conductor 22 passes through the bimetallic plate 24, which is similar to the plate 23 in every respect, to the load conductor 14. The plate or relay 24 will cause the circuit through the coil '11 to be interrupted when overload conditions occur in the load conductor 14. Therefore, overload conditions in either line will cause the switch to be opened.

Should low-voltage conditions prevail across the feed conductors 19 and 22, the current through the coil 11 will be diminish'ed to the point where the electromagnetic force can no longer retain the switch in closed position against the action of the spring tending to open it, with the result t at the circu1t is interrupted the moment a predetermined low-voltage condition ocours.

The switch mechanism illustrated in Figs. 1 and 2 is designed to accomplish the circuit control just described, and includes a metallic housing 37 having a cover 38 that is adapted to be clamped in closed position by means of latching devices 39 of a well-known type. The electromagnetic coil 11 is wound about one leg of a laminated magnetizable core member 41 having a leg 42 disposed parallel to the axis of the coil 11. The leg 42 is provided with hearing plates 43 through which the switch-operating shaft 4 extends and in which the shaft is rotatably supported.

A laminated movable armature 44 is fixed to the shaft 4 at a.point between the hearing plates 43 and serves to rotate the shaft in a counter-clockwise direction when the coil 11 of the electromagnet is energized.

The switch members 5, 6, 7 and 8 are secured, in spaced relation, upon the shaft 4, the switch arms 5 and 6 being disposed on one side of the field member, and the switch arms 7 and 8 are disposed on the opposite side thereof, as shown in Fig. 2.

An insulating bar 45 extends transversely of the housing in parallel relation to the shaft 4 and is secured to the field member 41 by means of a bracket 46. Terminals 47, 48, 49 and 51 are secured to the insulating bar 45 and are connected to the switch members 5, 6, 7 and 8, respectively, by means of flexible conductors 52, 53, 54 and 55, respectively.

Several of the innermost laminations of the armature 44 are provided with an extension 56 which projects from the pivoted end of the armature and to which one end of a helical spring 57 is attached. The other end of the s ring is attached to the insulating bar 45 y means of a screw 58. The spring serves to normally yieldingly retain the switch in open position, or to move it to open position, when the electromagnetic coil 11 is e-energized.

The electromagnet, including coil 11 and the magnetizable core member 41, the

movable switch arms and the terminals therefor are assembled to constitute a unitar structure which may be assembled exteriorly of the housing and placed therein as a unit, or bodily removed therefrom for the ur ose of inspection and repair, indepen ent y of the stationary contact members. This is a very desirable feature in connection with thi type of apparatus.

By reason of the construction wherein the switch shaft is mounted directly u on the.

electromagnetic field, bearings usua ly employed for supporting the switch shaft are eliminated and the construction considerably simplified. The mounting of the armature of the electromagnet directly on the shaft also provides a simple, compact ;--tructure which eliminates the mechanical structures usually employed for. connecting the arma ture to the switch member.

The stationary contact members 15, 16, 17 and 18 are mounted on fiat metallic conductor bars 59 and 61, the terminals 16 and 17 bein' mounted on the bars 61 which, as will hereinafter appear, are of different construction than the bars 59. The bars 59 are secured to an insulating bar.62 that extends transversely of the housing and is attached, at its ends, to the side walls thereof by means of metal brackets 63.

The conductor bars 59 are attached to the insulating bar 62. by means of terminal screws Get that extend through conductor bars 65. The latter bars are disposed in superimposed relation to the conductor bars 59 and are secured to the insulating bar on the side opposite that to which the bars 59 are attached.

The ends of the bars 59 and 65 terminate in the same plane and are each provided with yielding clips or receptacles 66 for receiving the thermal relays 23 and 24 which, for the purpose of convenience, are enclosed in casings similar to that of a cartridge fuse.

Such relays are well knownin the art and,

therefore, a detailed description thereof will not be necessary.

The stationary contact members 16 and 17 are secured to bars 61 which are attached to the underside of the insulating bars 62 by means of terminal screws 67 Inasmuch as all of the stationary contact members and relay devices are mounted upon the insulating bars 62, they may be assembled for inspection and repair as a unit, and bodily replaced within the hopsing, independently of the movable switch mechanism previously described.

The construction of the switch mechanism is relatively simple as compared with similarly functioning devices. Many of the parts are so designed that they may be stamped from sheet metal or formed from extruded metal strips. By reason of the compact and simple construction, the switch mechanism may be enclosed within a housing of relatively small dimensions and, therefore, of reduced cost. I

It willbe understood that the thermal re lays 23 and 24 may be adapted to have such thermal capacity to either protect a connected load or the conductors leading to that load. With the latter arrangement, the switch casing 37 may be disposed a considerable distance from the load, and relatively small conductors may be used from the switch boX to the load. This will result in a material saving in initial installation cost of a load, such as a motor.

lVhile I have described and illustrated but one embodiment of my invention, it will be apparent to those skilled in the art that various changes, modifications, substitutions, omissions and additions may be made therein without departing from the spirit and scope of mycinvention, as set forth in the appended claims.

I claim as my invention:

1. Switch mechanism comprising a movable switch member, a support, a pair of superimposed conductors mounted upon the support and insulated from one another, receptacles mounted on and supported by adjacent ends of the conductors for receiving a circuit-interrupting device and a contact member for engaging the switch member mounted on and supported by one of the conductors.

2. Switch mechanism comprising a housing, an electromagnet, a switch arm actuated thereby mounted within the housing and removable therefrom with the electromagnet as a unit, and a contact member within the housing for engaging the switch arm and having a circuit-interrupting device sup-- ported thereby and removable with the contact member.

3. Switch mechanism comprising a housing, a movable switch arm mounted therein, an insulating bar extending transversely of the housing and attached to the side walls of the housing, a terminal bar attached to one side of the insulating bar, a contact bar attached to the opposite side of the insulatlng bar and a current-responsive currenttontrolling device mounted upon and connecting the last said bars.

4. Switch mechanism comprising a housing, a movable switch arm mounted therein. an insulating bar extending transversely of the housing and attached to the side walls of the housing, a terminal bar attached to one side of the insulating bar, a contact bar attached to the opposite side of the insulating bar, a current-responsive current-controlling device, and receptacles mounted upon the last said bars for receiving the said device.

in testimony whereof, I have hereunto subscribed my name this 7th day of April, 1922.

CHARLES H. HODGKINS. 

